The present invention concerns a cylinder head gasket for sealing the region between the cylinder head and a cylinder block having a cylinder lining of an internal combustion engine.
Modern internal combustion engines increasingly have cylinder blocks of several components, in which, e.g., gray cast iron cylinder liners are cast or inserted into an aluminum block. This mode of construction also imposes new demands on a cylinder head gasket.
The rigidity of the engine with this modern construction is usually less than with a gray cast iron block such that distortions can occur more readily in the engine, which can also have an unfavorable effect on the seal between cylinder block and cylinder head.
Furthermore, especially with inserted cylinder liners, a relative movement between cylinder liner and the rest of the engine block cannot be excluded completely. Especially when the cylinder head is bolted on the cylinder block, the cylinder head gasket is subjected to a high pressure in the region around the combustion chamber passage opening to achieve a high surface compression. If this pressure is not distributed completely uniformly over the periphery of the cylinder, undesirable tilting moments or minor dislocations of the cylinder liner can take place relative to the rest of the cylinder block.
These effects require a cylinder head gasket whose combustion chamber-side seal functions flawlessly also with distortions, dimensional irregularities or improper handling.
DE 195 15 329 C1 shows a cylinder head gasket for sealing the region between cylinder head and the cylinder block of an internal combustion engine having a cylinder liner. It has two metal sealing sheets with an intermediate spacer sheet, where the metal sealing sheets have a combustion chamber crimp running around the combustion chamber passage openings. A stop serving as a path limiter for the combustion chamber crimps is provided on the side of the combustion chamber crimps facing away from the combustion chamber passage opening.
A movement or the introduction of unfavorable tilting moments should be prevented in that the cylinder liners have a peripheral outer edge at their cylinder head-side end, with which they are supported in a complementary recess of the cylinder block. In the case of dimensional irregularities of this expensive arrangement or distortions of the engine block, however, the sealing action of the combustion chamber crimps can be inadequate.
Based on this prior art, the goal of the present invention is to offer a cylinder head gasket that assures a permanently optimal sealing of the combustion chamber in interaction with the cylinder head, cylinder liner and the rest of the cylinder block.
This goal is achieved by a cylinder head gasket according to claim 1. Due to the fact that a sealing sheet has at least two concentric combustion chamber crimps, which are enclosed laterally by the stop, two subordinate protective dams are available in the radial direction, which can offer better height compensation and thus an improved sealing action in the case of a tilting of the cylinder liner relative to the engine block or a distortion of the engine block.
Particularly advantageous variants of the invention are shown in the dependent claims.
A particularly advantageous variant provides that the stop be designed as a thickening of the spacer sheet wherein the spacer sheet is located in the region of the combustion chamber passage opening essentially radially flush with the sealing sheet and the thickening relative to the combustion chamber passage opening is located on the side facing away from the concentric combustion chamber crimps.
It is particularly advantageous to design the stop additionally as a filled support crimp. The crimp cavity is filled here with an elastic-plastically deformable material, perhaps a hard-coating material. Such a support crimp, which is located in a power by-pass to the combustion chamber crimps, has the advantage according to the invention that relative movements can be made more difficult and leaks avoided. The filling of the support crimp, which is pressed on the lower sealing sheet or parts of the cylinder block when the cylinder head gasket is tightened down, serves as an additional seal. Such a seal is also adequate for the high pressures and long-term stresses of a truck Diesel engine.
Another advantageous variant provides that the cylinder head gasket be designed as a multilayer steel gasket with two sealing sheets and the spacer sheet between them, where all three layers have passage openings in alignment for water, oil, etc., and the spacer sheet has a sealing element of an elastomer around the throughflow opening. A secure seal that can be cost-favorably produced is thus made available for the throughflow openings for cooling water or oil with the remaining pressure of the cylinder head gasket, which was not consumed by the region around the combustion chamber passage openings.
A thickening containing an elastomer can be placed in the outer peripheral zone of the sealing sheet and be used as another advantageous variant, or a peripheral crimp as another variant.